Approximation (DP IB Applications & Interpretation (AI)): Revision Note

Approximating Values

How do I know what to round my answer to?

• Unless otherwise told, always round your answers to 3 significant figures (3 s.f.)

  • Remember: the first significant digit is the first non-zero digit (when reading from left-to-right)

    • Every digit after that is significant

• For currency

  • some systems use whole numbers

    • e.g. yen, yuan, peso

  • others use 2 decimal places

    • e.g. dollars, euro, pounds

Are there cases when I have to round up?

• There are some contexts when it makes sense to round up (or down)

  • e.g. if vehicles hold 5 people each, how many vehicles are needed to take 26 people?

    • which rounds to 5

    • However 5 vehicles isn't enough, so round up to 6